Two 12-year-old girls in Waukesha, Wisconsin, are facing attempted first-degree murder charges, as adults, after police say they stabbed a 12-year-old friend 19 times after a Friday home sleepover in celebration of a birthday.

Given permission by the mom in charge to go play in a nearby park the next morning, they told police they planned to kill their victim in a park bathroom because there was a drain on the floor for the blood, a lengthy Milwaukee Journal Sentinel article reports. However, the two girls hesitated to actually commit the crime and wound up stabbing their victim in another location in the park, police said.

The injured girl crawled from the woods where she was attacked, caught the attention of a bicyclist, and is now hospitalized, “fighting for her life,” the Journal Sentinel reported.

The two alleged perpetrators both told police they had acted to demonstrate their devotion to dedication to “Slender Man,” a fictional horror character they read about on the Internet, according to the newspaper. The plan was to find Slender Man’s home—which they believed to be in northern Wisconsin—after they killed their friend.

If convicted in the case, they could get as much as 65 years.

Bond was set at $500,000 for each of the girls when they were arraigned Monday in Waukesha County Circuit Court.

An attorney for one of the defendants says she shows signs of mental illness and needs to be hospitalized, the Associated Press reports.